The invention relates to a fuel injection pump for use in an internal combustion machine. The fuel injection pump includes a reciprocating and simultaneously rotating pump piston, serving as fuel distributor. The pump piston is provided at one end with longitudinal grooves that always communicate with the pressure chamber of the injection pump. During the rotation of the piston and during at least a portion of its suction stroke these grooves open suction channels partially extending in the injection pump cylinder and leading to the suction chamber of the fuel injection pump.
In order to insure proper filling of the pump pressure chamber during full-load and high r.p.m. engine operation, it is desired to maintain a long communication between the suction chamber and the pump pressure chamber during the suction stroke of the piston. For this purpose, the longitudinal grooves are made as wide as possible and, if possible, several longitudinal grooves are open simultaneously. However, the use of large control surfaces also requires a very precise shut-off so as to prevent different onset times of fuel delivery to the individual cylinders during the individual pressure strokes. In the known control process using longitudinal grooves, a considerable expense is required to obtain uniform shut-off of the suction channels during all fuel delivery strokes.